Pushable Implant Delivery System

ABSTRACT

An implant delivery system is described, having a distal tip and outer sheath that remain in a fixed position during implant delivery. A pusher mechanism within the sheath pushes an implant out of a gap between a distal end of the sheath and the distal tip.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 62/220,918 filed Sep. 18, 2015 entitled Pushable Implant DeliverySystem, which is hereby incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

Medical implants such as stents or stent grafts can be used to openblood vessels to mitigate the effects of plaque buildup, as a scaffoldto keep embolic material within an aneurysm, as a flow diverter to limitblood flow to certain regions, or for other reasons.

Some implant delivery systems have an outer tubular sheath that containsan elongated “pusher” member on which the implant is disposed. When thedistal end of the outer tubular sheath reaches its desired target site,the pusher member can be distally advanced to “push” the implant out ofthe sheath. In many of these types of delivery systems, the implant isdisposed over a portion of the pusher and the pusher further comprises adistal end portion located at or near the distal end of the cathetersheath.

In that regard, as the pusher is distally advance to deploy the implant,the pusher's distal end is advanced well beyond the distal end of thesheath. Depending on the shape and size of the vessel distal of thetarget site, such distal movement may cause the pusher to contactportions of the vessel beyond the deployed implant. Such contact mayresult in complications and therefore can be undesirable.

SUMMARY OF THE INVENTION

An implant delivery system is described. The implant delivery system canbe used for a stent and/or stent graft and/or other implants such ascoils, plugs, occluders, or other implants.

One embodiment is directed to a delivery system for a vascular implant,such as a stent, having a pushing mechanism configured to push the stentout of the end of an outer catheter sleeve or sheath without furtheradvancing any portions of the pushing mechanism distally beyond thedeployed stent. In other words, even as the stent is deployed, thedistal end member of the delivery system remains in a fixed locationrelative to the outer sheath and the vascular target site in thepatient. In this respect, undesirable contact distal of the deployedimplant may be reduced or eliminated.

In one embodiment an implant delivery system includes an inner tube anda pusher element.

In another embodiment an implant delivery system includes an inner tubeand a pusher element where the pusher element travels over the innertube.

In another embodiment an implant delivery system includes an inner tubewith a fixed position.

In another embodiment an implant delivery system includes an inner tubewhere the inner tube facilitates placement of a guidewire.

In another embodiment an implant delivery system includes an inner tubewith an enlarged distal section.

In another embodiment an implant delivery system includes a pusherelement where the pusher element contains one or more recesses toaccommodate an implant.

In another embodiment an implant delivery system is used to deliver astent and/or stent graft.

In another embodiment an implant delivery system is used to deliver astent and/or stent graft and includes a pusher element. The stent and/orstent graft has a structure which engages with one or more recesses onthe pusher element.

In another embodiment an implant delivery system includes a guidewireand a pusher element.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which embodiments ofthe invention are capable of will be apparent and elucidated from thefollowing description of embodiments of the present invention, referencebeing made to the accompanying drawings, in which:

FIG. 1 illustrates a side view of an implant delivery system with afixed distal end according to the present invention.

FIG. 2 illustrates a magnified view of a distal end of the deliverysystem of FIG. 1.

FIGS. 3 and 4 illustrate side views of the delivery system of FIG. 1deploying a stent.

FIGS. 5-7 illustrate various views of a sliding pusher element of thedelivery system of FIG. 1.

FIG. 8 illustrates an example stent that can be used with the deliverysystem of FIG. 1.

FIGS. 9 and 10 illustrate alternate embodiments of distal end membersaccording to the present invention.

FIGS. 11 and 12 illustrate alternate embodiments of an implant deliverysystem according to the present invention.

FIGS. 13-16 illustrate an alternate embodiment of an implant deliverysystem having a sliding tip member according to the present invention.

DESCRIPTION OF EMBODIMENTS

Specific embodiments of the invention will now be described withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art. Theterminology used in the detailed description of the embodimentsillustrated in the accompanying drawings is not intended to be limitingof the invention. In the drawings, like numbers refer to like elements.

FIGS. 1-4 illustrate a delivery system 100 for a vascular implant, suchas a stent 110, having a pushing mechanism configured to push the stent110 out of the end of an outer catheter sleeve or sheath 105 withoutfurther advancing any portions of the pushing mechanism or othercomponents distally beyond the deployed stent. In other words, even asthe stent 110 is deployed, the distal end member 102 of the deliverysystem 100 remains in a fixed location relative to the outer sheath 105and the vascular target site in the patient. In this respect,undesirable contact distal of the deployed implant may be reduced oreliminated.

As best seen in FIG. 2, the delivery system 100 includes an elongatedtube 106 that extends between the proximal and distal ends of thedelivery system 100. The proximal end of the elongated tube 106 is fixedin a non-retractable manner relative to the proximal components of thedelivery system 100 and terminates distally with the distal end member102. In this respect, once the delivery system 100 is advanced to adesired location within a patient, the elongated tube 106 and the distalend member 102 remain at that location during delivery, moving only whenthe entire delivery system is withdrawn from the patient.

Preferably, the outer sheath 105 is similarly fixed in a non-retractablemanner relative to the proximal components of the delivery system 100.In other words, the sheath 105 maintains a fixed position relative tothe tube 106 and distal end member 102. In that regard, the distal endof the sheath 105 is positioned a proximal distance from the distal endmember 102 (or from the largest part of the distal end member 102) so asto create a circumferential gap 101 through which the stent 110 can bepushed through (see FIGS. 3 and 4). Since the outer sheath 105 anddistal end member 102 are fixed from moving relative to each other, thecircumferential gap 101 remains present through all phases of thedelivery process.

In an alternate embodiment, the sheath 105 can be axially movablerelative to the distal end member 102, allowing a portion of the stent110 to be exposed.

The stent 110 is pushed out of the delivery system 100 by a slidingpusher element 104 that has an internal passage through which theelongated tube 106 is disposed. The pusher element 104 can thereforeslide axially along a portion of the tube 106 without also moving thetube 106, distal end member 102, or sheath 105. In other words, thepusher element 104 is independently moveable, allowing the tube 106,distal end member 102, and sheath 105 to have fixed lengths. The pusherelement 104 also releasably connects to a proximal end of the stent 110,which allows the pusher element 104 to distally push the stent 110, butalso proximally retract the stent 110 prior to its full release anddeployment.

Referring to FIGS. 5-7, in one embodiment, the stent 110 releasablyconnects to the pusher element 104 by enlarged bulbs 112 that are fixedon the proximal end of the stent 110 (such as on the proximal ends ofstent loops 111) and that fit into apertures or depressions on the outersurface of the pusher element 104. The sheath 105 maintains the bulbs112 in the depressions 104A, further preventing radial expansion of thestent 110. When the pusher element 104 moves distally beyond the distalend of the outer sheath 105, the proximal end of the stent 110 expands,allowing the bulbs 112 to move out of the depressions 104A and therebydisengage from the pusher element 104. In one embodiment, the depression104A is somewhat oversized relative to the bulbs 112 size, allowing forsome “play” or movement within the depression 104A.

The depression 104A preferably provides only an axial restraint to thebulb 112. If the depression 104A is large enough, the bulb 112 may alsohave some vertical movement (perpendicular relative to the axis of thedevice). However, preferably the overall clearance is limited in orderto limit the amount of wasted energy involved in pushing and pulling theimplant delivery device 100, as well as to limit the amount of jostlingthe stent 110 undergoes during delivery.

Radially, the bulb 112 and stent 110 are restrained by the sheath 105rather than depression 104A. However, other embodiments can utilize aradial limitation within the depression 104A. For example, thedepression 104A can take on the shape of a partial sphere with anoutward projection (e.g., a partial egg-shape) to restrict the bulb 112movement in a radial as well as an axial direction.

The stent 110 can be seen further in FIG. 8 and additional details ofthe bulbs 112 and its alternatives can be found in U.S. application Ser.No. 15/268,379, which is incorporated herein by reference. In oneembodiment, the stent 110 (or stent-graft) is comprised of a mesh ofwires. In one embodiment the implant is a stent or stent-graft comprisedof a mesh of wires and comprising two layers—an inner layer and an outerlayer. The wire meshes end at the proximal and distal ends of the stentleaving open pairs of wire ends. Cap or bulbs 112 may be placed overthese open wire ends to secure the open ends and to prevent the openends from traumatizing the vessel. Alternatively, instead of a cap, thewires may be welded together. The weld shape would be geometricallysimilar to bulbs 112. The cap can take on a number of shapes besides theshape shown in FIG. 8; a non-exhaustive list of examples includescircular, ovular, prism, pyramidal, ellipsoid, and hemispherical.Alternative embodiments for the bulbs 112 involve configurations wherethere is a cylindrical base to wrap around the wires and a proximal‘top’ structure which can be screwed, affixed, glued, or welded onto thebase. The ‘top’ structure would thus physically cover the proximal endsof the wires.

In one embodiment, the bulbs 112 of the stent 110 are all located at thesame radial position relative to each other. In another embodiment, someof the bulbs 112 are longitudinally offset from each other.

The pusher element 104 is axially moved by a connection to aphysician-actuated pusher rod 108. The pusher rod 108 is connected tothe pusher element 104 and to a handle 103 at the proximal end of thedelivery device 100, allowing the physician to move the handle 103proximally or distally to thereby move the pusher element 104 proximallyor distally. In one embodiment, the pusher rod 108 connects to thepusher element 104 at a location that is radially offset from a centerof the pusher element 104, allowing the tube 106 to pass through thecenter of the pusher element 104 (seen in FIGS. 5-7).

The distal end member 102 preferably has an elongated, conical region102B that proximally increases in diameter to reduce trauma as thedelivery device 100 is advanced through the patient. The distal endmember 102 also includes a reduced diameter region 102A that increasesin diameter in the distal direction, which helps radially expand anddirect outwards the distal end of the stent 110 as it is distallyadvanced within the sheath 105. Optionally, the very proximal portion ofthe distal end member 102 may also include depressions (similar todepressions 104A) that help maintain the position of the distal bulbs112 prior to the commencement of the stent 110 deployment. While onlythree depressions 104A are illustrated, it is contemplated that othernumbers of depressions 104A are also possible (e.g., between 1 and 16).Additionally, while the depressions 104A are all illustrated at the samelongitudinal position, it is contemplated that some can belongitudinally offset from each other.

The presence of distal end member 102 provides a few benefits. First, itprovides an atraumatic surface for minimizing blood vessel trauma duringtracking within the vasculature, since the distal end member 102 ispreferably made of a soft, polymeric material. Second, the distal endmember 102 provides a ramping surface for the implant (i.e., region102A). When the stent 110 is expelled from the sheath 105, it will openup relatively quickly since the stent 110 is kept in a restrained statedue to the compressive force of the sheath 105. Many implants are madeof a shape memory material, so they quickly adopt their expandedconfiguration when released from a sheath 105. Instead of an abruptopening, the region 102A provides a ramped, controlled opening as theinner surface of the stent 110 contacts the region 102A while the stent110 is pushed out. Such a controlled delivery is also beneficial to aidretraction. The tendency of an implant to adopt its expandedconfiguration can result in an abrupt implant opening and therefore theuser may not be able to pull the stent back after advancing to a certainpoint, prohibiting repositionability. As an example, once the majorityof the stent 110 is expanded, the opening force can transmit through therest of the stent 110, propelling it in premature delivery. If theimplant opens and is delivered too quickly, there is little time toreposition the implant once a portion of the implant opens. A morecontrolled delivery therefore allows the user more time and controlthroughout the delivery process.

The proximal region 102A of distal end member 102 preferably has arelatively abrupt transition region as shown in FIG. 2. However, thisregion 102A can be varied to create a region with a larger or a smallertaper. The remaining portions of the distal end member 102 may have arelatively consistent diametrical profile or may gradually taper to asmaller diameter as shown in FIG. 2. Other variations are possible,including abrupt tapering to a smaller diameter and/or larger diameterregion. A gradual taper to a smaller diameter may be desirable to limitthe potential contact surface area between distal end member 102 and theblood vessel, while also providing an atraumatic contact surface betweenthe delivery system 100 and the vasculature. Other shape possibilitiesare shown in FIGS. 9 and 10, such as an ovular or balloon-like shape107A, or a football-like shape 107B. Various other shapes are possiblefor the overall profile of distal end member 102.

The tube 106 and distal end member 102 preferably form a connectedpassage within their structure that extends from the proximal portion ofthe delivery device 100 and terminates at the distal end of the distalend member 102. This passage allows the delivery device 100 to betracked over a guidewire 118 that has been placed at the target deliverylocation within the patient (see FIG. 2). Alternately, the proximal endof the passage may terminate distally of the proximal portion of thedelivery device 100, creating a rapid exchange port 140 for“over-the-wire” use (see FIG. 11). In another alternate embodiment, thepassage can be used with an atraumatic wire 142, instead of or inaddition to the distal end member 102 (FIG. 12).

In FIGS. 3 and 4, the simplified views of the delivery system 100illustrate the operation for delivering the stent 110. First, aguidewire 118 is placed at or near a desired target location within thevasculature of a patient. Next, the delivery device 100 is tracked overthe guidewire 118 such that the guidewire 118 passes through the passageof the distal end member 102 and tube 106. Once the distal end of thedelivery device 100 is positioned at or near the target location, thephysician proximally advances the handle 103, thereby distally movingthe pusher rod 108, the pusher element 104, and the stent 110, while thetube 106, distal end 102 and outer sheath 105 remain in relatively fixedpositions. As the distal end of the stent 110 moves forward, the taperedor conical portion 102A of the distal end member 102 helps direct thestent 110 out through the gap 101 between the distal end of the sheath105 and the largest diameter portion of the distal end member 102.

Prior to the enlarged bulbs 112 of the stent 110 leaving the sheath 105,the physician may decide to retract the stent 110 back into the deliverydevice 100 through gap 101 and redeploy to better achieve a desiredstent 110 position. The handle 103 can be retracted proximally, causingthe pusher rod 108, the pusher element 104, and the stent 110 to moveproximally, recapturing the stent 110 back within the sheath 105.Finally, the stent 110 can be redeployed as noted above until the distalend of the stent 110 (e.g., the bulbs 112) have escaped the sheath 105.

FIGS. 13-16 are directed to an alternate embodiment of a delivery system150 that is generally similar to the previously described deliverysystem 100. However, the system 150 includes a distal tip member 152that is connected to a distal end of the stent 110 and slides distallyduring a deployment procedure. In this regard, the system 150 can bedelivered with the tip member 152 maintaining the distal end of thesheath 105 in a closed position, as seen in FIG. 13. As the stent 110 ispushed distally, it pushes the distal tip member 152 distally, creatingthe gap 101 between the sheath 105 and the tip member 152 through whichthe stent 110 is deployed, as seen in FIG. 14.

The distal tip member 152 is prevented from moving off the distal end ofthe tube 106 by stopper 154, which is fixed to the tube 106. As bestseen in FIG. 16, the distal tip member 152 has an interior passagehaving a distal, larger diameter region and a proximal, smaller diameterregion. The stopper 154 can pass into the larger diameter region 1526but is too large for the smaller diameter region 152C, therebypreventing the distal tip member 152 from moving further. The stopper154 has a generally cylindrical shape, but may alternately have aconical shape that decreases in the proximal direction.

As best seen in FIG. 15, the proximal end of the tip member 152 includesa plurality of depressions or surfaces to help engage the bulbs 112 onthe distal end of the stent. As the stent 110 is distally advanced, thebulbs 112 contact and push the tip member 152 until the stopper 154 isreached.

In one example, the inner tube 106 can be comprised of a polymer. Inanother example, the inner tube 106 is metallic.

In one embodiment, the maximum outer diameter of distal end member 102is equal to or larger than the inner diameter of sheath 105. In oneexample, the enlarged distal end portion 102, as well as the inner tube106, are polymeric.

In another embodiment, the inner tube 106 is movable. In thisembodiment, a user would separately manipulate the position of innertube 106 and pusher element 104, since it may be desirable to allow thepusher element 104 to translate relative to the inner tube 106 to limitthe amount of the inner tube 104 which is exposed outside the distal endof the sheath 105.

Alternate embodiments can utilize a shorter inner tube 106. The innertube 106 could traverse only a portion of the overall delivery systemlength and the sheath 105 would utilize a proximal port to accommodateinner tube 106.

In one example, the overall working length (i.e. length from theproximal end of the sheath 105 to the distal tip of the distal endmember 102) is about 90-150 centimeters, while the length of the rapidexchange embodiment (i.e. length from the proximal port 140—which is thestarting point of inner tube 106—to the distal tip of the distal endmember 102) is about 30-60 centimeters.

Other embodiments are also possible. For example, the pusher couldutilize a screw or ratchet system. In this embodiment, the rod would beenclosed within another lumen. The rod and separate lumen would eachcontain corresponding male-female interfaces to support a ratcheting orscrew-type system. The user would interact with knob at the proximal endof the system to push or pull the system. In one example, the knob iscomprised of a dial which can be turned in one direction to advance thesystem and turned in another direction to retract the system. Thissystem could also be automated via an electro-mechanical system wherethe knob could be turned in one direction to turn a motor to advance orpush the system forward, and the knob could be turned in anotherdirection to turn the system in another direction to retract thedelivery system.

Pusher element 104 is shown as a round device which sits around innertube 106. However, the pusher element 104 can take on a number ofshapes. It need not completely sit around the inner tube 106 and mayinstead sit just around a portion of the tube 106 (e.g., a hemisphere).Alternatively, the pusher element 104 can take the form of a sliderwhich slides solely on a circumferential portion of inner tube 106.Obviously, the smaller pusher element 104 is, the smaller the pusherelement surface area will be which corresponds to fewer depressions 112and/or retention structures to grasp the stent 110—however, a smallerpusher element 104 could be useful for a smaller implant where highretention strength is not necessary.

The implant delivery system can be used with a variety of implants, suchas stent, stent/grafts, coils, plugs, occluders, etc. Though the systemwas primarily described with regards to stent and/or stent-grafts, thesystem can also be with several other devices. For example, the systemcould work with an embolic coil by having a distal coil implantstructure and a connecting piece with an interface which connects to thepusher element 104 (similar to the bulb/depression arrangement of FIG.2). A detachment mechanism would sit between the coil implant andconnecting structure, where the connecting structure is thermally,mechanically, or electrolytically severed to effect delivery of theimplant.

Though the term sheath or catheter is used in the specification todescribe a delivery device which the implant delivery system isdelivered through, the implant delivery system can also be trackedthrough various delivery devices such as hypotubes or other systemswhich can be used as a vascular conduit which an implant is deliveredthrough.

Though the term inner tube is used to describe element 106 of thefigures, the tube 106 can take on a number of different cross-sectionalshapes including circular, ellipsoid, square, rectangular, prisms, etc.This list is meant to be non-exhaustive and illustrative.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

What is claimed is:
 1. A vascular implant delivery device comprising: an elongated member sized for delivery within a vascular system and having a distal end and a proximal end; a pusher element connected to and sliding relative to said elongated member; and, an implant releasably connected to said pusher element; wherein said pusher element is configured to slide towards said distal end of said elongated member to deploy said implant while said distal end of said elongated member maintains a fixed position within said vascular system.
 2. The vascular implant delivery device of claim 1, further comprising a tubular sheath disposed around said elongated member and said pusher element; wherein said tubular sheath is fixed from longitudinal movement relative to said elongated member.
 3. The vascular implant delivery device of claim 2, wherein a distal end of said tubular sheath is spaced proximally from said distal end of said elongated member so as to create a circumferential gap through which said implant is pushed through.
 4. The vascular implant delivery device of claim 1, wherein said pusher element is disposed around said elongated member.
 5. The vascular implant delivery device of claim 1, wherein said pusher element further comprises a plurality of depressions that are each sized to contain a bulb member fixed to said implant.
 6. The vascular implant delivery device of claim 1, wherein said pusher element is connected to a pusher rod; said pusher rod extending to a proximal end of said vascular implant delivery device to allow hand-actuated axial movement of said pusher element.
 7. The vascular implant delivery device of claim 1, wherein said distal end of said elongated member has a proximally tapered portion and a distally tapered portion.
 8. The vascular implant delivery device of claim 1, further comprising a passage opening at said proximal end and said distal end of said elongated member; said passage being sized to accommodate a guidewire.
 9. A vascular implant delivery device comprising: an elongated member sized for delivery within a vascular system and having a distal end and a proximal end; a pusher element connected to and sliding relative to said elongated member; and, an implant releasably connected to said pusher element; a tubular sheath disposed over said elongated tubular member and said pusher element; wherein said elongated member maintains a fixed position relative to said tubular sheath and within said vascular system.
 10. The vascular implant delivery device of claim 9, wherein said implant is a stent having a plurality of bulb members that are releasably engaged in a plurality of depressions on an outer surface of said pusher element; said stent extending at least partially between said pusher element and said distal end of said elongated member.
 11. The vascular implant delivery device of claim 10, wherein said pusher element is disposed around said elongated member and is connected to a pusher rod that extends to a proximal end of said vascular implant delivery device.
 12. The vascular implant delivery device of claim 11, wherein said elongated member further comprises a guidewire passage.
 13. The vascular implant delivery device of claim 12, wherein said distal end of said elongated member further comprises a proximally conical surface and a distally conical surface.
 14. The vascular implant delivery device of claim 9, further comprising a gap between a distal end of said tubular sheath and said distal end of said elongated member; said gap sized for passage of said implant when distally pushed through by said pusher element.
 15. The vascular implant delivery device of claim 9, further comprising a distal end member that is slidable at said distal end of said elongated member and is releasably connected with a distal end of said implant.
 16. A method of deploying an implant, comprising: advancing a pusher element distally within a delivery device while maintaining a fixed position of a distal end of said delivery device; and, pushing an implant out of said distal end of said delivery device.
 17. The method of claim 16, wherein said maintaining a fixed position of said distal end of said delivery device further comprises maintaining a fixed position of an outer sheath and an inner tubular member position within said outer sheath.
 18. The method of claim 17, wherein said pushing said implant out of said distal end of said delivery device is followed by retracting said implant back into said delivery device.
 19. The method of claim 17, wherein said pushing said implant out of said delivery device includes disengaging said implant from said pusher element. 